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How does ARGO work? How does ejector work in M4?


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I just ran a box of buckshots thru my new 11703. This is my first shotgun. I had a little trouble controlling the muzzle rise but I’m very happy with the kick.  Let’s see whether I will feel any pain on my shoulder tomorrow. I felt it last time when I rented a M2.


I like mechanic and gun work. Posts like that by Stranger Danger on the trigger module help a lot. Can somebody direct me to a post about how ARGO works? I see there are holes on the barrel feeding gas to the pistons. How do pistons absorb shock when being driven back?


How does the ejector work? This a spring loaded plunger where the chamber contacts the receiver and bolt.


BTY, the plastic trigger housing sucks. I chipped mine since I forgot to press the bolt release when putting back the trigger.


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Look up A&S Engineering trigger frames. They’re beautifully machined aluminum. 

The ejector is pretty easy. When the bolt travels rearward with the shell hooked on the extractor claw, the rim of the case makes contact with the ejector which directs it out the ejection port. Being spring loaded reduces wear and tear on the shotgun since it isn’t hitting an unmovable part. 

The ARGO system sounds more complex than it is. You saw the two ports from the barrel. Each port feeds the gas chamber of the ARGO system for each piston. The piston sits free floating in the system. With the bolt to the rear, you can hear them slide fore and aft as you tilt the shotgun. Inside the regulating portion of the ARGO system is a blast cup which is held in place by thick diameter springs. When the pressure exceeds the required amount of force set by the spring, the excess gas is able to vent out the front of the plug under the hand guards. The blast cup and pistons aren’t super tight fitting, so there is a lot of play to permit function once they get dirty. You’ll note the pistons have crud cutters and Chanel’s thru the middle section or each piston. These allow the gas to move freely forward against the piston to drive the bolt carrier rearward. It gives the crud a place to go too. 

Avoid oiling the pistons since they will burn it away quickly and turn the oil to carbon. It’s a pain to clean and does little to help function. The pistons are stainless so it isn’t likely that they’re going to rust on you. 

The system will function without pistons pretty reliably. I broke one piston and the shotgun kept running until the broken end of the piston jammed the action. Pulling back the bolt carrier and tilting the shotgun threw out the broken piece and it still functioned. 

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